1. Field of the Invention
The present invention relates generally to medical guide wires and catheters, and more particularly, to an apparatus and method for wetting guide wires, catheters, and other medical instruments of the type having an outer coating of a hydrophilic material or other lubricous coating which provides a slippery, reduced-friction surface when activated by a wetting fluid.
2. Description of the Prior Art
It is well known in the practice of medicine and veterinary science that instruments inserted into the body should have a low coefficient of friction between the instrument and surrounding tissues to facilitate ease of insertion and also to minimize trauma to the tissues surrounding the insertion tract. Such instruments include guide wires and catheters inserted into the vascular system, drainage catheters placed in fluid-secreting organs, such as the kidney and liver, as well as endotracheal and bladder catheters. Similarly, angiographic procedures commonly involve the placement of catheters within blood vessels for treating vascular irregularities. Other examples of tubular instruments which are inserted into the body for diagnosis and treatment include endoscopes for examination of the bowel or urinary tract, as well as ultrasound probes for insertion into blood vessels, bowel, or reproductive organs.
Until recently, instruments of the type described above included a smooth finish applied by carefully polishing the surface in contact with the body, or by application of a substance such as flouro-plastics, silicone or teflon (manufactured by DuPont). Although such polishing technique and surface coatings reduce the amount of friction for such medical instruments, the remaining friction between such instruments and surrounding tissues is still significant.
More recently, newer materials which further decrease the coefficient of friction have been introduced. Such newer materials are known as hydrophilic coatings and include a water soluble polymer applied to the surface of the instrument. Such hydrophilic polymers include cellulosic polymers, polyacrylamide, maleic anhydride polymers, and water soluble nylon. Such hydrophilic coatings are also known in the medical field as hydrogel coatings, and represent one form of a lubricious coating that is activated by a wetting fluid to provide a slippery surface when so activated. Coatings of these materials over medical instruments significantly decrease frictional resistance between such coated medical instruments and the human body. Similarly, such coatings significantly decrease frictional resistance when a coated instrument is passed through another instrument.
The application of various hydrophilic coatings to guide wires, catheters, and other medical instruments is described within U.S. Pat. Nos. 4,705,709 (Vailancourt); 4,798,593 (Iwatschenko); 4,876,126 (Takemura et al.); 4,906,237 (Johansson et al.); 4,977,901 (Ofstead); and 4,990,357 (Karakelle et al.).
Commercial forms of hydrophilic-coated medical guide wires are available from such companies as Medi-tech, Incorporated of Watertown, Mass., which company markets guide wires of various lengths, thicknesses, and tip configurations under the trademark "Glidewire"; these guide wires are manufactured by Terumo Corporation of Tokyo, Japan and include an outer hydrophilic coating to reduce friction when wet. Such medical guide wires include a super-elastic metallic core for strength and a hydrophilic outer coating for reduced friction. The packaging instructions direct the user to prime the catheter to be passed over the guide wire with heparinized physiological saline before attempting to pass the catheter over the guide wire. The directions further advise that the use of sterilized gauze moistened with physiological saline aids in its handling. Angiographic catheters having hydrophilic outer coatings have also been made commercially available recently.
A disadvantage of such hydrophilic coatings is the requirement that they be continuously wet to maintain their lubricity during use. Furthermore, if such a coated instrument is first wetted and then allowed to dry, the coated surface passes through a phase where the surface becomes somewhat tacky and has a much higher coefficient of friction as compared to the end phase when the coating has completely dried. It is therefore essential to wet those parts of the instrument which lie outside the body before any manipulation can occur.
By way of example, a guide wire is commonly used for inserting and exchanging catheters within the vascular system. The technique for inserting a catheter within the vascular system consists of first establishing a path through the patient's skin into a blood vessel, as by the use of an introducer needle. A guide wire is then inserted through the introducer needle and guided into the blood vessel until the distal tip of the guide wire has advanced to the point of interest. The introducer needle may then be removed, and a catheter is then advanced over the proximal end of the guide wire, through the skin entry point, and along the blood vessel until the distal tip of the catheter reaches the end of the guide wire. The guide wire may then be withdrawn, leaving the catheter in place. If such a guide wire has a hydrophilic coating, it is necessary to wet the guide wire before inserting the proximal end of the guide wire into the distal end of the catheter. However, if the guide wire begins to dry off before the catheter has been fully advanced thereover, the hydrophilic coating can become tacky and resist further advancement of the catheter thereover. Bent-end catheters, such as Simmons catheters and pigtail catheters, are particularly troublesome because of the extra time needed to straighten the curves in order to get the catheter loaded onto the guide wire.
Guide wires are also commonly used for exchanging catheters in the vascular system. The technique for exchange consists of placing the guide wire through a catheter already in the vascular system and removing the catheter from the blood vessel by sliding it over the guide wire and removing the catheter therefrom. The portion of the glide wire that lies outside the patient is wiped with a wet sterile 4.times.4 gauze pad to remove any residual blood after a catheter is withdrawn thereover. A new catheter is threaded over the guide wire into the vascular system until the distal end of the guide wire is reached and the guide wire is then removed.
If a hydrophilic guide wire is used to perform this procedure, then certain precautions are necessary. When the first catheter is withdrawn during such a catheter exchange operation, the portion of the guide wire that is visible outside the catheter must be wetted to maintain lubricity; otherwise, as the catheter is withdrawn, the frictional force developed between the catheter and guide wire will cause both the catheter and the guide wire to be removed from the blood vessel, resulting in a loss of access to the vascular system.
Once the first catheter has been successfully removed from the guide wire, and the second catheter is to be threaded over the guide wire, the portion of the guide wire lying outside the body must be wetted once again; otherwise, it may be very difficult to thread the second catheter over the guide wire.
In view of the requirement for maintaining the guide wire wet, it is currently necessary for a physician to require the presence of an assistant to keep the guide wire wet while the physician inserts or removes a catheter during an angiographic procedure. For example, during the procedure of inserting a catheter over a guide wire, the physician typically keeps one of his hands at the skin entry point to anchor the guide wire against movement and to prevent bleeding. The physician's other hand usually grasps the distal end of the catheter to advance it over the guide wire. Typically, a nurse or other assistant must take a sterile gauze pad, soak the pad in sterile water, and wipe the guide wire to wet the surface before the physician can advance or retract the catheter. However, it is difficult for the physician and the assistant to coordinate the wiping movement of the gauze pad and the advancement of the catheter so that they are moved at the same rate. The requirement for continued wiping of the guide wire is a nuisance. Moreover, wiping such guide wires with gauze pads can leave a residue which adheres to the surface of such guide wires.
By way of a further example, catheters are often introduced into a blood vessel through a sheath previously placed in a blood vessel or organ. In other cases, catheters are directly introduced through the patient's skin without the use of a sheath. If the catheter includes a hydrophilic coating over its outer surface, the catheter must be wetted prior to insertion through such a sheath or through the patient's skin. Even if the catheter is initially wetted, a delay of only one or two minutes during the insertion procedure can be enough to result in increased friction when the catheter is advanced through the sheath or through the patient's skin, making it much more difficult to pass the catheter into the patient's body.
Devices have been proposed in the past for lubricating, coating, or otherwise engaging catheters. For example, U.S. Pat. No. 3,3456,988 (Vitello) describes a catheter lubricating sac having a lubricating chamber of generally tubular configuration for applying a lubricant to the shaft of a catheter passed therethrough before inserting the catheter into the body. However, such device is not adapted to wet a guide wire over which a catheter is to be passed. Further, such device must be manually supported and is not adapted to be releasably secured to a sheath or to the patient's body for lubricating a catheter as the catheter is being inserted into a patient's body.
U.S. Pat. No. 3,606,889 (Arblaster) discloses a guard accessory for use with a retention type urethral catheter to prevent bacteria from spreading along the exposed portion of the catheter. The device is designed to slide over a portion of the catheter, and includes cushions which wipe against the surface of the catheter. The cushions are porous and are impregnated with an antibiotic ointment which is dispensed along the walls of the catheter. Again, such device is not adapted to wet a guide wire over which a catheter is to be passed. Further, the device is neither designed for, nor capable of, coating the entire length of the catheter as the catheter is being inserted into the patient's body. In addition, the device may not be easily removed from the catheter after the catheter is placed in the body; indeed, it is the purpose of such device to remain fixed on the catheter after the catheter is placed within the body.
U.S. Pat. No. 3,721,252 (Ayella) describes a spray head in the form of a ring coupled to a syringe for rinsing blood from a spring guide wire of the type introduced into blood vessels. The spray head has a central bore through which the spring guide wire is passed. The spray head directs water jets at the spring guide wire as the syringe is depressed. The device is threaded over a guide wire and moved to a point adjacent the entry site and advanced back toward the proximal end while a saline-heparin solution is expelled through the device by a syringe to rinse any blood from the guide wire. The device does not wipe the walls of the spring guide wire, and no means are provided for supporting such device adjacent a catheter, sheath, or adjacent the patient's body. The device is somewhat cumbersome since it requires that one hand of the physician or an assistant be used solely to support and depress the syringe.
U.S. Pat. No. 3,871,358 (Fukuda et al.) describes a guide tube having a passageway through which an endoscope may be passed and includes a liquid-absorbable foam impregnated with a lubricant for lubricating the walls of the endoscope being passed therethrough. However, such a device would not lend itself to use for threading the distal tip of a catheter over a hydrophilic-coated guide wire and is not readily detachable after a medical instrument has been placed within the body.
U.S. Pat. No. 4,784,647 (Gross) describes a device to prevent infection from entering the body along the exposed portion of a urinary tract catheter. A cylindrically shaped block of foam material includes a central bore for receiving the catheter and has a radial slit formed therein to allow the catheter shaft to be inserted into the bore of the foam material. The foam may be impregnated with an antibiotic material that is applied to the wall of the catheter and forms a dressing at the tip of the urethra. The device is not adapted to slide along a catheter to coat the surface with a sliding action; to the contrary, the device includes a circular boss to frictionally engage the shaft of the catheter to prevent displacement of the device once positioned.
U.S. Pat. No. 4,834,711 (Greenfield et al.) describes a medical appliance to lubricate and disinfect urethral catheters or venous catheters. The appliance includes a central conduit through which the catheter extends. A reservoir communicates with the central conduit to introduce lubricant thereto. However, the device is not easily detachable from a catheter that has already been placed in the body, nor are means provided for supporting such a device upon the proximal end of a sheath, nor upon the distal tip of a catheter being threaded over a hydrophilic-coated guide wire.
While the above-described devices are believed to perform useful functions within the applications and uses for which they were designed, it does not appear that any of such devices overcomes the difficulties noted above in conjunction with the use of hydrophilic-coated guide wires, catheters, and other medical instruments.
Accordingly, it is an object of the present invention to provide an apparatus and a method for wetting hydrophilic-coated medical instruments to facilitate insertion of such instruments into the body or through other instruments.
It is another object of the present invention to provide such an apparatus and method which is simple to use, allowing a physician to perform such procedures without the assistance of a nurse or other assistant.
It is a further object of the present invention to provide such an apparatus and method which neither leaves a residue upon, nor adheres to, such hydrophilic-coated surfaces.
Various forms of catheters include hooked or curved distal tips. Such catheters include the Simmons-style, which in its relaxed state, includes a distal tip portion shaped in the form of a Shepherd's crook. Other examples of flexible catheters having curved ends include Cobra tip catheters, and J-Hook catheters and so-called pigtail catheters. Such catheters are commercially available from such companies as Cook Company of Bloomington, Ind. It is often difficult to thread a guide wire into the distal end of such curved-end catheters unless the distal tip of the catheter is first straightened.
Accordingly, it is another object of the present invention to provide such an apparatus and method for wetting a guide wire while simultaneously straightening the distal tip of the catheter to facilitate insertion of the guide wire into the distal end of the catheter.
Still another object of the present invention is to provide such an apparatus and method for wetting a catheter or other medical instrument that includes a hydrophilic outer coating before such instrument is advanced into a sheath, through the patient's skin, or into a patient's orifice.
Yet another object of the present invention is to remove blood or other residue from the guide wire by a wiping action while simultaneously wetting the guide wire to reduce friction.
A further object of the present invention is to provide such a wetting apparatus which can be manufactured inexpensively and easily for disposable use.
A still further object of the present invention is to provide such a wetting apparatus in a form which can be packaged together with various catheters, guide wires, or other medical instruments to provide a ready means for easily and conveniently maintaining the hydrophilic-coated surfaces thereof wet and slippery.
These and other objects of the present invention will become more apparent to those skilled in the art as the description thereof proceeds.